A gas turbine engine may be used to power various types of vehicles and systems. A particular type of gas turbine engine that may be used to power aircraft is a turbofan gas turbine engine. A turbofan gas turbine engine may include, for example, five major sections: a fan section, a compressor section, a combustor section, a turbine section, and an exhaust section. The fan section is positioned at the front or inlet section of the engine and includes a fan that induces air from the surrounding environment into the engine and accelerates a fraction of this air toward the compressor section. The remaining fraction of air induced into the fan section is accelerated into and through a bypass plenum and out the exhaust section.
The compressor section raises the pressure of the air it receives from the fan section to a relatively high level. In a multi-spool engine, the compressor section may include two or more compressors, such as, for example, a high pressure compressor and a low pressure compressor. The compressed air from the compressor section then enters the combustion section, where a ring of fuel nozzles injects a steady stream of fuel into the compressed air. The fuel-air mixture is ignited in the combustion section to generate combustion gases. The high-energy combustion gases from the combustion section then flow into and through the turbine section, thereby causing rotationally mounted turbine blades to rotate and generate energy. The air exiting the turbine section is exhausted from the engine via the exhaust section, and the energy remaining in the exhaust air aids the thrust generated by the air flowing through the bypass plenum.
In some engines, the compressor section is implemented with a centrifugal compressor. A centrifugal compressor typically includes at least one impeller that is rotationally mounted to a rotor and surrounded by a shroud. When the impeller rotates, it compresses the air received from the fan section and the shroud directs the air radially outward into a diffuser. The diffuser decreases the velocity and increases the static pressure of the air and directs the air into a deswirl assembly, which straightens the flow of the air before it enters the combustor section. The combustor section in some engines is implemented with an axial through-flow combustor that includes an annular combustor disposed within a combustor housing. The straightened air enters the combustion section and travels axially through the annular combustor where it is mixed with fuel and ignited.
The effectiveness of the aerodynamic coupling between the sections of the gas turbine engine impacts engine performance, operability and efficiency. To achieve optimal performance for a system, particularly one with a centrifugal compressor, the discharge flow from the centrifugal compressor is typically conditioned in an attempt to provide desired pressure and velocity characteristics. However, when an axial combustor is used in conjunction with the centrifugal compressor, efficiently directing air between the compressor and combustor may pose challenges.
Accordingly, there is a need for improved systems and methods for aerodynamically coupling sections of a gas turbine engine, particularly between a centrifugal compressor and an axial combustor to suitably direct and condition air flow for optimal performance. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.